The present invention relates to a power transmission control device, a power reception control device, a non-contact power transmission system, a power transmission device, a power reception device, an electronic instrument, and the like.
In recent years, non-contact power transmission (contactless power transmission) which utilizes electromagnetic induction to enable power transmission without metal-to-metal contact has attracted attention. As application examples of non-contact power transmission, charging a portable telephone, a household appliance (e.g., telephone handset), and the like has been proposed.
JP-A-2006-60909 discloses a non-contact power transmission device using a primary coil and a secondary coil, for example.
In a charging device utilizing non-contact power transmission disclosed in JP-A-6-339232 and a non-contact power transmission system disclosed in JP-A-11-146569, a power-receiving-side device detects that a secondary battery has been fully charged and notifies a power transmission device that charging has completed, and the power transmission device then stops power transmission.
A non-contact power transmission system disclosed in JP-A-2005-6459 detects an abnormality in load (i.e., an open state or a low-load state has occurred) when supplying power, and causes a power transmission device to decrease the oscillation frequency of an oscillation circuit so that heat generation or breakage of components is prevented.
When a secondary battery is connected to a charger after completion of charging, the battery voltage gradually decreases due to a discharge from the secondary battery. Therefore, it is desirable to recharge the battery, if necessary.
According to the technologies disclosed in JP-A-6-339232 and JP-A-11-146569, since power supply from the power transmission device is completely stopped after the battery of the power reception device has been fully charged, it is impossible to recharge the secondary battery after completion of charging.
The technology disclosed in JP-A-2005-6459 aims at preventing heat generation or breakage of components due to an abnormality in load when supplying power, and does not take recharging into consideration.